Existing drive systems for rolling curtains/doors employ roller barrels for rolling up and deploying curtains/doors. However, there is a limit to the width of the driven door for each barrel, based on the deflection that occurs to a barrel once it exceeds a certain length due to the barrel weight and/or the weight of the curtain or door. For example, it has been found that a 4-inch diameter barrel can extend across an opening of 24 feet, after which too much deflection of the barrel will occur. Likewise, a 3-inch diameter barrel can extend across an opening of 18 feet. But if such a barrel is made longer, the same problem of deflection will occur.
One response for traversing larger spans has been to employ barrels in a staggered configuration with each being operated by a respective motor, which barrels are synchronized together. Each barrel supports and controls a designated curtain segment and the barrels turn at the same rate so that the different curtain segments will lower and raise together. This arrangement is costly and requires multiple motors, which is undesirable with regard to, for example, motor synchronization.